Check in ...East Coast BLACKOUT

"Dr. Anthony J. Lomenzo" wrote:

While we're on the subject of 'juice' so to speak, in every power outage
up here in the north country [upstate NY] the phones are mercifully
still much welcomed operation but, here's the thing, while it's common
knowledge that the phone system wires carry their own juice, well, even
those wires have to have a source for their power generation! Where is
it and note that even in extensive power grid failures like the nation
just experienced, the phones came through! So where is their source?

The basic phone system runs on 48 volt DC. Most switches are located in
"Central Offices". These are manned stations. These contain battery banks,
which are constantly charged by commercial power supplies. Each office has
diesel generators to power chargers in the event of a power loss.

Developed areas which are not fairly close to small cities (or larger metro
areas) may connect to a "remote switching unit". These are located in unmanned
offices. These offices have backup power of some sort, usually diesel, but it
is expected that field personel will come out within a day or two to make sure
everything's OK. They cannot run indefinitely in backup mode.

Areas which are located far enough from the office will be served by digital
communication means. Multiplexed varieties of these systems are used in high
traffic areas, whether close to the C.O. or not. These digital centers and
optional multiplexers are located in unmanned stations. In the northeast, these
are usually underground in "controlled environment vaults". These CEVs have
battery backup power, but usually don't have generators. This requires that
field personel show up shortly with backup generators in an extended power
loss.

From your viewpoint, it doesn't matter if the CEV went down, the RSU went down,
or the CO went down. If any of the three happen, your phone is dead.

George Patterson
Brute force has an elegance all its own.